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The ageing and deterioration of highway bridges can have serious consequences in terms of reduced safety and serviceability. The objectives of this paper are to present an approach for the structural health monitoring of concrete bridge structures; and to demonstrate the effective use of field monitoring data for the updating of service life prediction models, which accuracy can be significantly improved. A case study on a major highway bridge is also presented and used to illustrate the approach., INFRA 2008: 17 November 2008, Quebec city

A considerable percentage of highway bridges in North America is in a structurally/functionally deficient state due to aging, aggressive environment and increased traffic load and volume. The consequences of this deficiency are numerous, including reduced safety, serviceability and service life, which lead to increased risk of injuries and fatalities; and increased maintenance costs and user costs. Reliable predictions of life cycle performance are critical to the optimization of their design and maintenance that will lead to reduced risks of failure and life cycle costs., Annual Conference of the Transportation Association of Canada (TAC): 21 September 2008, Toronto, Ontario

High performance concrete (HPC) bridge decks are prone to premature cracking if movement is restrained. Internal curing (IC) can reduce shrinkage cracking in structures, thus improving their performance and service life. However, there is very limited information in the literature on the possible extension of service life due to internal curing. This paper addresses this question by using predictive models to estimate the service life and life-cycle costs of a typical bridge deck made with concrete using internal curing as opposed to conventional curing. Four options are compared: (i) normal concrete deck; (ii) HPC deck; (iii) HPC deck with internal curing; and (iv) very high performance concrete deck with internal curing. It was found that the use of internal curing can extend the service life of HPC bridge decks by almost ten years, which is mainly due to due a slower penetration of chlorides as a result of reduced shrinkage cracking. The use of internal curing in HPC decks resulted in a 20% reduction in life-cycle costs, even though the in-place unit cost of internally-cured HPC can be up to 4% higher than that of conventionally-cured HPC. The higher initial investment for the construction of the HPC-IC deck can be offset in only 5 years when compared to that required for normal concrete deck. This is due to a longer service life and less frequent maintenance activities., 50th Brazilian Concrete Congress "Concrete Infrastructure and Environmental Conservation": 04 September 2008, Salvador, Brazil

This paper evaluates relationships between four parameters that govern the time to corrosion initiation of reinforced concrete in chloride-laden environments ' the concrete chloride diffusion coefficient, the steel reinforcement chloride threshold, the concrete cover depth, and the surface chloride exposure condition. A deterministic diffusion-based corrosion initiation model was used to determine numerical, nonlinear relationships between pairs of parameters based on a deterministic, diffusion-based, corrosion initiation model. The relationships can be used to determine the most appropriate combination of the parameter values for an effective design., The 2nd Canadian Conference on Effective Design of Structures: 20 May 2008, Hamilton, Ontario

With its very high strength, high modulus and very low permeability, ultra high performance concrete (UHPC) can provide major improvements over conventional high performance concrete (HPC) in terms of structural efficiency, durability and cost-effectiveness if used in the construction of slab-on-precast prestressed girder bridges. In this study, the optimum use of UHPC is evaluated for the case of simply supported cast in place concrete slab on precast/prestressed UHPC girder bridges. These bridges are designed according to the Canadian Highway Bridge Design Code requirements, including no cracking at the serviceability limit state., Second International Symposium on Ultra High Performance Concrete: 05 March 2008, Kassel, Germany

Workshop on Computational Tools and Technologies for Construction Practitioners: 13 February 2008, London, Ontario

This study investigated the optimum use of ultra high performance concrete (UHPC) for two- and three-lane simply supported bridges. Two designs were investigated: (i) typical cast in place concrete slab on precast/prestressed UHPC girders; and (ii) typical cast in place concrete slab on precast/prestressed UHPC girders. The study measured stress distributions and concentration zones in the girders under dead- and traffic-loads. The concrete quantities and the total areas of prestressing steel were calculated for the UHPC designs and compared to typical concrete designs., 2007 PCI National Bridge Conference: 21 October 2007, Phoenix, Arizona

This paper presents a life cycle-based approach for the design of concrete highway bridges that takes into account physical, economic and environmental performance with emphasis on the reduction of greenhouse gas emissions, construction waste production, and life cycle cost. The analysis considers all the key stages in the life cycle, which include extraction of raw materials, construction, maintenance, repair, rehabilitation, replacement, and disposal. The life cycle analysis compares the life-cycle performance of two concrete highway bridge decks built in corrosive environments - normal concrete is used for one and high performance concrete for the other., 3rd International Conference on Life Cycle Management: 27 August 2007, Zurich, Switzerland

ACI Workshop on Advances in Service Life Models that Consider Multiple Sources of Deterioration, 24 April 2007, Atlanta, Georgia

Aussi disponible en français: Pour une meilleure gestion du cycle de vie des tabliers de ponts routiers

Both owners and users of bridges expect them to have a service life of 50 to 100 years, with only routine maintenance. But demands on most of our bridges have been increasing annually because of growing traffic volumes, higher loads, and harsher environments. These conditions, coupled with the inadequate funding allocated for maintenance, have led to the accelerated aging and extensive deterioration of these critical structures.

This paper presents a comprehensive approach to life cycle cost analysis of reinforced concrete bridges that takes into account all costs incurred by the owners and users during construction, maintenance rehabilitation and replacement. This approach provides also an estimate of the environmental impacts associated with construction and replacement of bridge decks in terms of greenhouse gas emissions and waste production. The analysis considers all the key stages in the life cycle, which include extraction of raw materials, construction, maintenance, repair and rehabilitation, replacement, and disposal. The total life cycle costs are evaluated by using the present value method. In this paper, the long-term economic efficiency of high performance concrete (HPC) containing supplementary cementing materials for the construction and rehabilitation of concrete bridges is evaluated and compared to that of normal performance concrete (NPC) in terms of service life, life cycle cost and environmental impacts., Infra 2006 - Le Québec en chantier : optimiser les interventions

Cet article présente deux différents types de modèles fiabilistes pour la prévision de la durée de vie des tabliers de ponts en béton qui permettent une gestion efficace de la maintenance des ouvrages d'art. Le premier modèle est de type mécano fiabiliste où la performance physique de la dalle est décrite par une fonction appelée marge de sécurité, qui mesure la différence entre la résistance de la dalle et les effets des charges mécaniques et/ou environnementales sur la dalle. Ce type de modèle est utilisé pour prédire la variation avec le temps de la probabilité de défaillance de la dalle. Les différents temps pour atteindre les différents états de défaillance correspondant à différents états limites peuvent être prédis incluant les états de corrosion des armatures, fissuration, délaminage, éclatement du béton d'enrobage, et rupture. Un autre type de modèle qui prédit l'accumulation de l'endommagement de la dalle comme un processus stochastique a été développé. Dans ce modèle, la durée de vie de la dalle est prédite comme le temps ou l'état absorbant est atteint. L'intégration de ces deux modèles permettra une gestion optimale des tabliers de ponts, Also published in "Recueil des Commuications du 13e Colloque sur la Progression de la Recherche sur les Ouvrages d'Art, Transports Québec, Québec, QC. May 9, 2006, Infrastructures durables: Techniques, outils et guides, Regard sur la science du bâtiment 2006, 1 October 2006

This paper presents a new approach for the maintenance optimization of concrete bridgedecks, which combines a stochastic deterioration model and a multi-criteria optimizationmodel. The stochastic deterioration model is based on the first-order Markov chain thatpredicts the probabilistic time-variation of the condition of bridge decks. The multicriteriaoptimization model takes into account two important and conflicting criteria: theminimization of maintenance costs, and the maximization of the network condition. Thisapproach generates the solution that achieves the best compromise between thesecompeting criteria, while considering the uncertainty in bridge deck deterioration. Thefeasibility and capability of the proposed approach is demonstrated on a network ofbridge decks obtained from the Ministère des Transports du Québec database. Thisexample illustrates the effectiveness of the proposed approach in determining theoptimal set of maintenance alternatives for reinforced concrete bridge decks whenconsidering two or more relevant optimization criteria., 7th International Conference on Short & Medium Span Bridges: 23 August 2006, Montreal, QC.

Publicly owned infrastructure forms a large portion of the existing infrastructure in Canada and elsewhere. Typically, asset managers must make decisions about maintenance and renewal alternatives based on sparse data about the current state of their infrastructure assets, the relative risk of failure of these assets, and the life cycle costs of proposed interventions. The infrastructure in any one organization can consist of a diverse set of assets ranging from bridges to buildings and from buried to overhead utilities. The optimal selection of proposed interventions across this broad spectrum of assets is also problematic, and currently it is performed in a subjective manner. This paper identifies a number of prioritization techniques that can be used to compare and rank repair and renewal projects. This research does not attempt to develop models to select the 'correct projects' or even to identify the best decision model or prioritization technique; rather, it attempts to illustrate by example the results of specific decision-making paradigms., Joint International Conference on Computing and Decision Making in Civil and Building Engineering: 14 June 2006, Montréal, QC.

This paper presents a new approach to optimizing the maintenance of concrete bridge decks. This approach combines a stochastic deterioration model and a multiobjective optimization model. The stochastic deterioration model is based on the first-order Markov chain, which predicts the probabilistic time variation of bridge deck conditions. The multiobjective optimization model takes into account two important and conflicting criteria: the minimization of maintenance costs and the maximization of the network condition. This approach achieves the best compromise between these competing criteria while considering the uncertainty in bridge deck deterioration. The feasibility and capability of the proposed approach are demonstrated with field data for a sample network of bridge decks obtained from the Ministère des Transports du Québec database. This example illustrates the effectiveness of the proposed approach in determining the optimal set of maintenance alternatives for reinforced concrete bridge decks when two or more relevant optimization criteria are taken into consideration.

The corrosion of reinforcing steel in reinforced concrete (RC) bridge decks due to the application of de-icing salts in winter has been recognized as one of the major causes of highway bridge deterioration in North America. Corrosion-induced damage is usually manifested by longitudinal cracking, spalling, and/or delamination of the concrete cover due to the expansion of corrosion products accumulating around the reinforcement. This damage leads to reduction or loss of serviceability, safety, and service life of RC bridge decks. This paper presents finite element analyses of the behaviour of the concrete bridge deck cover subjected to reinforcing steel corrosion. The prediction of the damage caused by corroding reinforcing bars is established by calculating the induced stresses in the surrounding concrete. The numerical model is used to conduct a parametric investigation of several design variables. It is found from the analyses that different failure mechanisms govern depending on the geometry and configuration of the reinforcing bars in the concrete cover of the bridge deck. Finally, the impact of concrete overlays on the governing failure modes of cracking, spalling and/or delamination of the concrete cover is investigated by using the model., 1st Canadian Conference on Effective Design of Structures, July 10, 2005, Hamilton, Ontario, Canada

Aussi disponible en français: De nouveaux outils d'aide à la décision facilitent la gestion du cycle de vie des tabliers de pont en béton

Aussi disponible en français: En bref - L'IRC lance un projet de recherche sur l'analyse du cycle de vie et la durabilité des structures en béton à haute performance (BHP)

This paper presents an approach for bridge maintenance optimization that takes into account several and possibly conflicting criteria, with emphasis on risk of failure as a governing criterion. The optimal maintenance strategy is defined as the solution that achieves the best compromise between three selected relevant and conflicting criteria: minimization of risk of failure, minimization of maintenance costs, and minimization of traffic disruption. Compromise programming is used to determine the optimal ranking of the maintenance strategies in terms of their effectiveness in risk reduction, cost minimization, and traffic control. A multi-criteria optimality index is proposed as a measure of the effectiveness of the optimal maintenance strategy in achieving a satisfactory trade-off between the above relevant and competing maintenance criteria. The proposed approach is illustrated on a small network of ten bridge projects that are optimized for maintenance by considering the three selected criteria. The weighted and non-weighted multi-criteria indices are generated for these projects., 2nd International Colloquium on Advanced Structural Reliability Analysis Network (ASRANet), Organized by International Center for Numerical Methods in Engineering: 05 July 2004, Barcelona, Spain

This paper presents an approach to programming maintenance alternatives for a network of concrete bridge decks using genetic algorithms and Markovian performance prediction models. Genetic algorithms are robust and stochastic optimization techniques that overcome the mathematical complications and combinatorial explosion problems of the conventional optimization techniques. Markovian models are the state-of-the art stochastic models used in several maintenance management systems to predict the future condition for a network of infrastructure facilities. An illustrative example for finding the optimal maintenance alternatives for concrete bridge decks using field data is presented to demonstrate the feasibility and capability of the proposed approach., Annual Conference of the Canadian Society for Civil Engineering, 4 June 2003, Moncton, N.B.

This paper presents a probabilistic approach for predicting the chloride contamination of concrete and reinforcement corrosion, which takes into account the uncertainty associated with the analytical models of chloride transport, corrosion initiation, and damage accumulation, material properties, structural dimensions, and applied environmental and mechanical loads. The proposed approach is illustrated on an aging reinforced concrete bridge deck that has been exposed to chlorides from deicing salts for forty years. An extensive non-destructive and destructive evaluation of the corrosion-damaged deck was undertaken. The field survey data showed a considerable level of variability in all parameters measured with coefficients of variation ranging from 34% for the concrete cover depth to 86% for the diffusion coefficient. The distributions of the chloride concentration at the level of the top reinforcement mat and the time for its corrosion initiation were generated using Monte Carlo Simulation. The simulated results were very close to the field data, which illustrates the prediction capabilities of probabilistic methods as opposed to deterministic methods, as well as to some non-destructive evaluation methods., 3rd International IABMAS Workshop on Life Cycle Cost Analysis and Design of Civil Infrastructure Systems & FIB-JCSS Workshop on Probabilistic Modeling of Deterioration Processes in Concrete Structures, March 24, 2003, Lausanne, Switzerland

Infra 2002: 25 November 2002, Montreal, QC, Canada

This paper presents a two-level approach for the maintenance management of aging highway bridges that integrates two different probabilistic deterioration prediction models. The level-1 management is based on Markovian cumulative damage models that predict the macro-response of bridge structures. The level-2 management is based on quantitative reliability-based mechanistic deterioration models that predict themicro-response of bridge structures. The level 1-management identifies the critically damaged structures and forecasts the overall deterioration and required maintenance funds for both short and long term planning for a bridge network or a bridge component. The level-2 management focuses on the critical structures that were identified from the level-1 management or from a specific condition assessment to evaluate their safety and serviceability, and optimize their maintenance. The proposed two-level approach to bridge maintenance management, which integrates two different probabilistic deterioration models, will help improve the effectiveness of maintenance management systems in satisfying the safety, serviceability, andbudgetary requirements of highway agencies., 7th ASCE International Conference on Applications of Advanced Technology in Transportation: 05 August 2002, Boston, MA., U.S.A.

The results of a comprehensive condition assessment of a decommissioned reinforced concrete bridge, which included both a field survey and laboratory tests are presented. The field survey included electro-chemical, chemical, physical and mechanical tests on the bridge deck, which was exposed to a corrosive environment for about 35 years. The experimental study focused on the investigation of the impact of concrete mix on corrosion and subsequently on the bond strength of concrete structures. The data collected from the field survey include measurements of concrete cover depth, chloride content, half-cell potential, electrical resistivity, and level of carbonation. These data shows a considerable level of variability in all parameters measured with coefficients of variation ranging from 34% for the concrete cover depth to 86% for the apparent chloride diffusion coefficient. A Monte Carlo simulation was undertaken to generate the distributions of the chloride content at the reinforcement level and corrosion initiation time for the deck. Thesimulations generated results that were very close to the field data. Partial results of the experimental study of the impact of corrosion on bond shows a quasi-linear decrease of the residual bond capacity with the mass loss of reinforcing steel., 6th International Conference on Short and Medium Span Bridges: 31 July 2002, Vancouver, B.C.

Bridge management systems (BMSs) are developed to assist decision-makers in optimizing the allocation of their limited budget on maintenance needs of bridge networks. Reliable deterioration models are essential constituents of BMSs that are used to predict the remaining service life of bridge components. The deterioration models incorporated in the recent BMSs have limitations that can be accepted for the analysis at the network level but not at the component level. Moreover, the current mechanisticdeterioration models developed for the component level analysis are neither versatile nor adequately extensible to predict the service life of a large number of bridge components, or to incorporate additional deterioration parameters. Therefore, an artificial intelligence approach 'Case-Based Reasoning (CBR)' is proposed to develop extensible, reliable, and generic deterioration models for the analysis at the component level. The CBR approach is utilized to predict the time to corrosion initiation of the reinforcing steel inconcrete bridge decks. Data obtained from the Dickson Bridge in Montreal are used to generate the cases that populate the case library of the CBR model by applying the Monte Carlo Simulation techniques. Parameters that significantly affect the deterioration rate of concrete decks, such as the concrete cover thickness, apparent diffusion coefficient, and surface chloride concentration, are considered., 6th International Conference on Short and Medium Span Bridges: 31 July 2002, Vancouver, B.C.

Many transportation agencies have recently adopted bridge management systems (BMSs) tooptimize decisions related to the expenditure of their limited funds on bridge maintenance,rehabilitation, and replacement (MR&R). The analysis in most of these BMSs is based on thelife-cycle assessment of different MR&R alternatives for a network of bridges. This assessmentrequires reliable prediction of the condition of different bridge components when various MR&Ractions are implemented (including the 'do nothing' option). The state-of-the-art systemsconsider the use of the stochastic Markov chain models in predicting the bridge performance.This stochastic approach can predict the condition of a bridge component at any time usingpredefined transition probabilities obtained by expert judgment elicitation procedures. In thispaper, the actual condition data obtained from the Ministére de Transport du Québec (MTQ) areused to develop transition probabilities for concrete bridge decks. These probabilities areemployed to validate those developed based on the literature and engineering judgment. Inaddition, a subset of the data is utilized to validate the state independence assumption of Markovchains., Proceedings of the 2002 Taiwan-Canada Workshop on Bridges: 08 April 2002, Taipei, Taiwan

This paper presents a systematic decision-making approach for asset maintenance management that combines a stochastic Markovian performance prediction model with a multi-objective optimization method for determining the optimal allocation of funds and prioritization of assets for maintenance, repair and replacement. The maintenance optimization is formulated as a multi-stage and multi-objective optimization problem that seeks the simultaneous satisfaction of several conflicting objectives. The paper also examines the benefits of this approach as compared to the traditional maintenance prioritization and management practices., 9th International Conference on Computing in Civil and Building Engineering: 03 April 2002, Taipei, Taiwan

This paper summarizes the first stage of research for the Building Envelope Life Cycle Asset Management (BELCAM) Project for developing techniques to predict the remaining service life of building envelope components and procedures to optimize their maintenance. Data were collected on 2800 roof sections from a wide range of systems and climatic regions across Canada according to age, material type, geographic location and condition of the roofing sections. Techniques were developed for estimating the life cycle costs for different maintenance strategies and the risk of envelope failure and a prototype, graphical, decision-support tool was developed., 9th International Conference on the Durability of Building Materials and Components: 17 March 2002, Brisbane, Australia

This paper provides an overview of the development of software-based decision support tools for service life prediction and rehabilitation of corrosion-damaged concrete bridge decks. The proposed tools consist of a reliability-based service life prediction model and a life cycle costing model that will assess the impact of alternative rehabilitation strategies on extending the life of bridge decks and their costs., Supersized Session on Asset Management, APWA International Public Work Congress: 08 September 2001, Philadelphia, PA

Aussi disponible en français: En bref - un logiciel d'aide à la décision pour estimer la durée de vie utile et planifier la réhabilitation des tabliers de pont en béton

Proceedings of the Third International Conference on Concrete under Severe Conditions: Environment & Loading: 18 June 2001, Vancouver, B.C.

This paper presents a probabilistic approach to life prediction of concrete highway bridge decks based on Bogdanoff''s cumulative damage model. The condition of the deck is discretized into a finite set of damage states including no damage, onset of corrosion, crack initiation, major damage and failure. The damage accumulation process is modeled using a stationary unit jump Markov chain in which the probability distribution of damage after a duty cycle is assumed to depend only on the length of the duty cycle and the damage accumulated at the start of the cycle. The service life is determined from the time to reaching the absorbing state, which may successively be redefined as the onset of corrosion, cracking, spalling, etc. The proposed model is simple to use and the statistics of the lifetime and damage states at any given time are easily determined. The model yields a practical tool for the condition assessment, life prediction, and maintenance management of highway bridge decks. An example illustrating the application of the proposed approach is presented., Proceedings of International RILEM Workshop on Life Prediction and Aging Management of Concrete Structures: 16 October 2000, Cannes, France

Aussi disponible en français: En bref - Un consortium se penche sur la question de l'entretien des ponts en béton

CERIU-Infra 99 International Convention: 22 November 1999, Montreal, Quebec

8th International Conference on the Durability of Building Materials and Components: 31 May 1999, Vancouver, B.C.

A service life prediction approach for roofing membranes and systems is proposed based on a probabilistic modeling of the time-dependent performance. The membrane performance is modeled using a discrete Markov chain that evaluates the change of performance over time as a result of deterioration or repair. This stochastic model will be developed using in-field performance data collected during roof inspections, considering the roofing system type, membrane type, age group, exposure conditions, and maintenance level. The use of in-field performance data captures the interaction between roofing components, as well as the synergism of the various degradation factors. The probabilistic modeling accounts for the uncertainty and variability of material properties, degradation factors, and quality of workmanship and maintenance. The service life is determined considering both the technical and economical performance, in addition to the risk of failure, this constitutes the first step towards the standardization of service life prediction of roofing membranes and systems., Roofing Research and Standards Development, 4th: 08 December 1998, Nashville, TN., U.S.A.

Construction and the Environment - CIB World Building Congress: 07 June 1998, Gavle, Sweden

Developments in Short and Medium Span Bridge Engineering '98: 13 July 1998, Calgary, Alberta

First International Conference on New Information Technologies for Decision Making in Construction: 11 October 1998, Montreal